1. Field of the Invention
The present invention relates to optical devices, and more particularly, to a method for the recovery of a damaged table of contents (TOC) in an optical disc.
2. Description of the Prior Art
Recordable optical discs provide a portable, affordable, and flexible format in which a user can store and transport data. Some of the common optical disc formats today include BD (Blue ray discs), HD-DVD (High Density DVD discs), DVD, and CD. Although there are several formats of optical disc types on the market, most share similar characteristics and structures. Burning of recordable disc is usually performed in sessions (For HD-DVD and DVD-R, “session” is also referred as “Border”). The sessions can either be open—indicating that further data can be stored within the session, or closed, meaning that no further data can be added to the session. No more than one open session can exist on a single optical disc, and only the last session on the disc can have the possibly of being the open session.
Surrounding each session is a temp-leadin area and temp-leadout area. The temp-lead-in area precedes the session recording, and the temp-lead-out area follows the session. Generally, these areas provide a buffer area between subsequent sessions (however for BD-R, there is no temp-lead-in and temp-lead-out surrounding for each session). Each closed session should contain a file system for management of data within each session. Before the current using session is closed, a host system will write file system data into these areas to convey file distribution information for management purposes according to the file system specification. Common file system specifications include Universal Disc format (UDF) and ISO09660 for various types of optical disc formats.
The sessions of the optical disc are further divided into segments for which specific data is stored into. Depending on the type of optical disc used, the segment is referred to by a specific name. For BD discs, the segment is called an SRR, for DVD+R discs it is called a fragment, for HD-DVD-R discs and DVD-R discs it is called a recording zone (Rzone), and for CDRs it is called a track. In order to simplify the discussion to follow, the term SRR will simply be used to refer to all the above segment types. It should also be noted that a session can contain multiple SRRs.
Information regarding each individual session (including distribution and status), and their SRRs, are contained within a table of contents (TOC). According to the physical specification of the disc, its TOC possesses a reference location of each session and data format of the disc. The data of the TOC is stored in a TDMA area or DMA area with SRRI format for BD-R discs, the TOC Zone with SDCB format for DVD+R discs, the RMD area with RMD format for HD-DVD-R and DVD-R discs, and stored in PMA area with TOC format for CD-R discs.
In the case of sequential recording, the TOC also provides the disc drive a location corresponding to the first SRR starting location in the last open session. This location can be used to determine a starting location in a following open session for continuation of recording if desired.
When a host system or computer wants to access an optical disc, it must first request the disc drive to read the TOC. After reading the TOC, the disc drive can return the TOC reference information to the host. The host can then identify session and SRR data through parsing the requested TOC information. Critical information includes the start location (the start location of a certain session corresponds to the start location of the first SRR of the certain session in this application) of the first session, the start location of the last closed session, and the start location of the last open session. These start locations are used as references in subsequent reading and writing operations performed on the disc.
Occasionally, an optical disc drive may be incapable of reading the TOC of the optical disc due to recording defects, scratches on the disc surface, or dust interfering with a laser of the disc drive. If this happens, the disc drive will not be capable of accessing certain data (or sessions) within the optical disc. The disc drive will also respond to the requesting host with an error message indicating its inability to read the TOC. Depending on the damaged or unreadable area(s) in the TOC, the drive may not be able to reference and read certain areas in the disc. Furthermore the host may not be able to receive the latest updated TOC information, and will therefore be unable to properly perform subsequent writing and reading operations on the disc without a reference for the last closed session.